Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (37,551)us-gaap_ProfitLoss	$ 3,446us-gaap_ProfitLoss	$ 4,966us-gaap_ProfitLoss
Net Income (Loss) Attributable to Parent	(36,644)us-gaap_NetIncomeLoss	3,446us-gaap_NetIncomeLoss	4,966us-gaap_NetIncomeLoss
Income Taxes Paid, Net	(233)us-gaap_IncomeTaxesPaidNet	(278)us-gaap_IncomeTaxesPaidNet	4,694us-gaap_IncomeTaxesPaidNet
Operating activities:
Depreciation, Depletion and Amortization	10,443	4,307	2,286
Amortization of Financing Costs and Discounts	329	0	0
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	5,000us-gaap_Depreciation	4,189us-gaap_Depreciation	2,188us-gaap_Depreciation
Share-based compensation	22,665us-gaap_ShareBasedCompensation	16,272us-gaap_ShareBasedCompensation	9,645us-gaap_ShareBasedCompensation
Excess tax benefits on share-based compensation	0	(2,940)	(1,686)
Tax Benefit from Stock Options Exercised	(110)	2,931	1,573
Deferred income tax	12,638us-gaap_DeferredIncomeTaxExpenseBenefit	(2,776)us-gaap_DeferredIncomeTaxExpenseBenefit	962us-gaap_DeferredIncomeTaxExpenseBenefit
Provision for doubtful accounts	(192)us-gaap_ProvisionForDoubtfulAccounts	300us-gaap_ProvisionForDoubtfulAccounts	(326)us-gaap_ProvisionForDoubtfulAccounts
Tangible Asset Impairment Charges	4,040us-gaap_TangibleAssetImpairmentCharges	0us-gaap_TangibleAssetImpairmentCharges	0us-gaap_TangibleAssetImpairmentCharges
Changes in operating assets and liabilities:
Accounts and unbilled receivables	(14,026)pro_AccountsAndUnbilledReceivables	(7,492)pro_AccountsAndUnbilledReceivables	(4,609)pro_AccountsAndUnbilledReceivables
Prepaid expenses and other assets	(3,383)	1,204	2,215
Accounts payable	(3,104)	2,885	(790)
Accrued liabilities	(1,080)	1,002	1,700
Accrued payroll and other employee benefits	3,289	1,050	2,879
Deferred revenue	7,796	(3,218)	5,837
Net cash provided by operating activities	1,754	16,971	24,652
Investing activities:
Purchases of property and equipment	(7,499)	(3,401)	(7,514)
Capitalized Software Development Costs for Software Sold to Customers	(2,305)	(2,874)	(2,013)
Increase in restricted cash	39,718	(39,389)	0
Net cash used in investing activities	7,866	(58,766)	(9,527)
Financing activities:
Exercise of stock options	1,105	3,327	1,354
Excess tax benefits on share-based compensation	0	2,940	1,686
Proceeds from Stock Plans	335us-gaap_ProceedsFromStockPlans	0us-gaap_ProceedsFromStockPlans	0us-gaap_ProceedsFromStockPlans
Tax withholding related to net share settlement of restricted stock units	(13,089)	(3,342)	(2,814)
Noncontrolling Interest, Increase from Business Combination	(6,147)	0	0
Business combination, payment of contingent consideration	(2,225)	0	0
Proceeds from Convertible Debt	138,631us-gaap_ProceedsFromConvertibleDebt	0us-gaap_ProceedsFromConvertibleDebt	0us-gaap_ProceedsFromConvertibleDebt
Proceeds from Issuance of Warrants	17,106us-gaap_ProceedsFromIssuanceOfWarrants	0us-gaap_ProceedsFromIssuanceOfWarrants	0us-gaap_ProceedsFromIssuanceOfWarrants
Purchase of convertible bond hedge	(29,411)pro_Purchaseofconvertiblebondhedge	0pro_Purchaseofconvertiblebondhedge	0pro_Purchaseofconvertiblebondhedge
Debt Issuance Cost	0us-gaap_DebtIssuanceCosts	0us-gaap_DebtIssuanceCosts	(250)us-gaap_DebtIssuanceCosts
Net cash (used in) provided by financing activities	106,305	2,925	(24)
Effect of Exchange Rate on Cash and Cash Equivalents	406	0	0
Net increase in cash and cash equivalents	116,331	(38,870)	15,101
Cash and cash equivalents:
Beginning of period	44,688	83,558	68,457
End of period	161,019	44,688	83,558
Interest Paid	(243)us-gaap_InterestPaid	(87)us-gaap_InterestPaid	(68)us-gaap_InterestPaid
Capital Expenditures Incurred but Not yet Paid	1,140	2,045	1,425
SignalDemand [Member]
Investing activities:
Payments to Acquire Businesses, Net of Cash Acquired	0	13,102	0
Cameleon Acquistion [Member]
Investing activities:
Payments to Acquire Businesses, Net of Cash Acquired	$ (22,048)	$ 0	$ 0

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